Communication services such as voice calls have traditionally been provided via circuit switched (CS) networks, such as the Public Switched Telephone Network (PSTN) or cellular wireless networks. In addition to establishing a circuit for the voice call, network elements on the communication network may provide particular services on the call to enable different functions to be implemented on the call. For example, a user may wish to block caller ID so that, when the call is dialed through to the intended recipient, the user's caller ID may not be viewed. Likewise, a person may wish to have privacy on the call to prevent other third parties from interrupting the call. Many types of services have been developed, and are typically accessed by having the person dial a “vertical service code” when first initiating the telephone call on the network. In the US, vertical service codes are typically invoked by dialing “*” and then a service code number before dialing the telephone number. In other jurisdictions, vertical service codes may require the user to use a different symbol, such as the “#” symbol, or require the user to dial a particular series of digits such as “11”.
In addition to invoking services before the call is initiated, other services may be invoked while the call is underway. These services are commonly referred to as “mid-call services”. For example, a person on a telephone call may wish to add additional parties to the telephone call. Rather than terminate the first call, the person may seek to add the additional parties to the call by invoking a mid-call service (conference call service) on the existing connection.
Traditionally, services extended to second generation (2G) wireless devices are provided directly by the wireless access network, e.g. by the Mobile Service Center, Home Location Register, and possibly the Service Control Point. Conventionally, mid-call services on a 2G wireless network could be invoked in one of two ways. In the first case, the mid-call service could be invoked using a menu from the phone, such as Unstructured Supplementary Service Data (USSD) techniques within Global System for Mobile communications (GSM) networks. USSD provides a data messaging capability similar to text messaging that is built into the GSM standard.
The second way that mid-call services could be invoked in a 2G mobile network was using in-band DTMF tones. In that scenario, the media path of the active call would be monitored so that any tones applied by the user to activate a mid-call service could be detected and reported to the Mobile Service Center. Although the term “call” will frequently be used herein to refer to a voice communication session, the term “call” is intended to be interpreted in a broader sense to refer to other types of communication sessions as well. For example, the term “call” also encompasses video telephony, streaming media, and other types of communication sessions that may be established by a mobile device on a communication network.
With the advent of fixed mobile convergence, there is a strong desire in the marketplace to be able to deliver a converged set of services to both wireless and wireline devices. This will serve to extend additional services to the mobile user, and do so in such a way that is backwards-compatible to existing 2G mobile devices. This allows additional centrex business services to be extended to mobile devices, and increases the set of mid-call services that are possible to invoke on an existing voice session. However, the traditional mechanisms for invoking mid-call services (noted above) can impose limitations on the solution when used with these new business services. For example, the new service may not be integrated into the service set supported by USSD, or the media resources needed to monitor for in-band DTMF tones may be cost-prohibitive. As the potential set of services grows with new business services in Fixed to Mobile convergence solutions, it would be advantageous to provide a process of enabling mid-call services to be added to a call on a mobile telephone network.